Gun barrel weapons of the type described in German published application No. DE-OS 21 02 310 are well-known and utilize a propellant charge requiring no cartridge casing which is axially slidably and/or helically shaped so as to be axially movable in the weapon. This propellant charge having no cartridge casing includes a propellant medium combustion chamber in ellipsoidal form adapted for high cadence firing of projectiles. There is also described in an article entitled "Raketenantrieb" (rocket propulsion) by M. Barrere, Elsevier Publishing Company 1961/page 450 known combustion chamber forms which, when used with gun barrel weapons, with liquid propulsion medium can cause with unfavorable burning of the propulsion medium an incomplete combustion. This occurs because the high pressure combustion chamber which is equipped with pressurizing means there occurs, after combustion ignition, a blocking of the exit opening of the combustion chamber, whereby the progressing reaction is interrupted or inhibited so that at simultaneous projectile movement it can again restart and the process can be cyclically repeated. Due to the non-uniform combustion there remain unburned propellant material remnants in the chamber. As a result of the thereby simultaneously occurring strong pressure oscillations an unstable projectile flight can occur.